Recent acceleration of Greenland and Antarctic outlet glaciers and ice flows is closely linked to ocean warming, especially in the subsurface layer. This land ice melt will cause sea level rise.

We find that in response to an increase in atmospheric greenhouse-gas concentrations, the subsurface oceans (200-500 m) surrounding the two polar ice sheets both warm substantially more than has been observed thus far. Model projections suggest that the maximum ocean warming around Greenland will be double the global mean, whereas ocean warming around Antarctica will be only half the global mean (see figure).

A detailed evaluation indicates that the climate mechanisms behind the projected warming are likely realistic and capable of driving substantial increases in ice mass loss and sea level rise in the future. A more accurate simulation and projection of ice sheets and their interactions with the ocean and the atmosphere require refined resolution Earth system models, which resolve fast-moving ice flows and small-scale temperature changes.

The availability of these models in the future would significantly advance our understanding of ice sheet dynamics, and in turn improve sea level rise projections. Until then, these results suggest substantial dynamic ice sheet mass loss due to continued ocean warming should be considered a real possibility.

Figure. Projections of subsurface (200-500 m) ocean warming during 2091-2100 and 2191-2200 under the A1B scenario. Warming along the land-ocean boundary of Greenland and Antarctica, together with the global mean in the same layer. Grey dots and dashed lines indicate the projections by individual models and the ensemble mean, respectively. Red and blue circles indicate the GFDL CM2.0 and CM2.1 results, respectively.